The present invention relates generally to a radio-frequency identification (RFID) tag device that is designed to operate on difficult substrates. Specifically, the RFID tag is created in a roll to roll process with a series of cavities formed in the substrate to establish a separation between the antenna and the difficult substrate.
Radio-frequency identification (“RFID”) is the use of electromagnetic energy (“EM energy”) to stimulate a responsive device (known as an RFID “tag” or transponder) to identify itself and in some cases, provide additionally stored data. RFID tags typically include a semiconductor device commonly called the “chip” on which are formed a memory and operating circuitry, which is connected to an antenna. Typically, RFID tags act as transponders, providing information stored in the chip memory in response to a radio frequency (“RF”) interrogation signal received from a reader, also referred to as an interrogator. In the case of passive RFID devices, the energy of the interrogation signal also provides the necessary energy to operate the RFID device.
RFID tags may be incorporated into or attached to articles to be tracked. In some cases, the tag may be attached to the outside of an article with adhesive, tape, or other means and in other cases, the tag may be inserted within the article, such as being included in the packaging, located within the container of the article, or sewn into a garment. The RFID tags can contain a chip that is manufactured with a unique identification number which is typically a simple serial number of a few bytes with a check digit attached. The user cannot alter this serial/identification number and manufacturers guarantee that each serial number is used only once. This configuration represents the low cost end of the technology in that the RFID tag is read-only and it responds to an interrogation signal only with its identification number.
Alternatively, the RFID chips included in the RFID tag may include memory that can be written to after manufacture, so information about the product that the RFID tag is attached to may be programmed in at other locations, such as at the point of manufacture of the item or at a location where a visual feature, such as a barcode, pattern or human readable is printed, allowing said information to be associated with the printed information. In this case, the RFID tag can respond to the interrogation signal with all or part of the programmed information as well as a unique number if that has been programmed into a read only memory structure at point of manufacture.
The RFID tag, depending on what type of chip is used, may be associated with an item in a database using the unique number, or by the relationship between the programmed data and the item. The objective of the tag is to associate it with an article or multiple articles associated in a bag or other container. This information may be used at one or more location depending on the use case; typical examples would be in a manufacturing facility, a transport vehicle, in a shop, a health care facility, a pharmacy storage area, or other environment. It will be appreciated that the use of the data in the RFID tag and where it is accessed is dependent on what the tag is to be used for. For example, tracking the articles through the facility can assist in generating more efficient dispensing and inventory control systems as well as improving work flow in a facility. This results in better inventory control and lowered costs. It is also desirable to develop accurate tracking, inventory control systems, and dispensing systems so that RFID tagged devices and articles may be located quickly should the need arise, and may be identified for other purposes, such as expiration dates or recalls.
Many RFID tags used today are passive in that they do not have a battery or other autonomous power supply and instead, must rely on the interrogating energy provided by an RFID reader to provide power to activate the tag. Passive RFID tags require an electromagnetic field of energy of a certain frequency range and certain minimum intensity in order to achieve activation of the tag and transmission of its stored data. Another choice is an active RFID tag; however, such tags require an accompanying battery to provide power to activate the tag, thus increasing the expense and the size of the tag and making them undesirable for use in a large number of applications.
Depending on the requirements of the RFID tag application, such as the physical size of the articles to be identified, their location, and the ability to reach them easily, tags may need to be read from a short distance or a long distance by an RFID reader. Furthermore, the read range (i.e., the range of the interrogation and/or response signals) of RFID tags is also limited.
Furthermore, when the RFID tags are attached to a difficult substrate, such as dielectrics with high loss, for example, organic materials like meat, and metallic surfaces and/or conductive surfaces, typically a standard RFID tag cannot be read as efficiently as one placed on other materials such as clothing, corrugate boxes etc. This is a significant problem given that in many commercial applications it is desirable to apply the RFID tag to a difficult substrate, such as dielectrics with high loss, and metallic or other types of conductive surfaces. In order for an RFID tag to work (operate) on these difficult substrates, performance is greatly increased by establishing a separation between the substrate and the antenna structure. This separation must then be filled with a suitable dielectric, such as foam or plastic, or air. What is needed therefore is an RFID tag device and/or system that allows the RFID tag to operate in proximity to difficult substrates, such as dielectrics with high loss, and/or metal surfaces or other types of conductive surfaces, by creating a separation between the substrate and the antenna structure.
The present invention discloses an RFID tag device that is designed to operate on difficult substrates, such as dielectric surfaces with high loss, organic material surfaces, or metallic surfaces, and an associated manufacturing method to reduce cost and allow efficient production. The RFID tag device comprises an RFID antenna structure formed on one side of a thermoplastic substrate component with an RFID chip coupled to it. The substrate component is then deformed into a series of cavities with the RFID antenna structure within the cavities to create a separation between the substrate and the RFID antenna structure.